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Severe Weather Threat May 17-19, 2025
- Thread starter Brice W
- Start date
Sorry I've been MIA due to ongoing weather affecting family members. We're all good, pending what today brings
Ebaad Jaffery
Member
Mesoscale Discussion #874
SUMMARY...An increase in strong thunderstorm development appears possible through Noon to 2 PM CDT. This may include evolving supercells, accompanied by a risk for tornadoes, in addition to large hail. Trends are being monitored for the possibility of a severe weather watch.
DISCUSSION...A few cells have begun intensifying within a broader area of convective development now spreading northeast of the I-35 corridor of central Texas. This appears to have been initially supported by large-scale forcing for ascent associated with warm advection based near the 700 mb level, downstream of a mid/upper perturbation within the belt of westerlies emanating from the lower-latitude eastern Pacific. However, the stronger convective cores have probably begun to acquire updraft inflow emanating from the seasonably moist boundary-layer.
The downstream downstream environment remains capped by an elevated mixed layer based near/above 850 mb, but is warming with insolation. Coupled with the forcing for ascent, erosion of the inhibition may allow for a substantive further increase in stronger thunderstorm development during the next several hours. This may include a few intensifying supercells. In the presence of at least modestly enlarging, clockwise curved low-level hodographs, this activity may become accompanied by a risk for tornadoes, in addition to large hail.
SUMMARY...An increase in strong thunderstorm development appears possible through Noon to 2 PM CDT. This may include evolving supercells, accompanied by a risk for tornadoes, in addition to large hail. Trends are being monitored for the possibility of a severe weather watch.
DISCUSSION...A few cells have begun intensifying within a broader area of convective development now spreading northeast of the I-35 corridor of central Texas. This appears to have been initially supported by large-scale forcing for ascent associated with warm advection based near the 700 mb level, downstream of a mid/upper perturbation within the belt of westerlies emanating from the lower-latitude eastern Pacific. However, the stronger convective cores have probably begun to acquire updraft inflow emanating from the seasonably moist boundary-layer.
The downstream downstream environment remains capped by an elevated mixed layer based near/above 850 mb, but is warming with insolation. Coupled with the forcing for ascent, erosion of the inhibition may allow for a substantive further increase in stronger thunderstorm development during the next several hours. This may include a few intensifying supercells. In the presence of at least modestly enlarging, clockwise curved low-level hodographs, this activity may become accompanied by a risk for tornadoes, in addition to large hail.
Kds86z
Member
This is the early first round btw. When it ends it doesn’t mean tornado threat is done.
From Reed
Live emergency update on tornado outbreak expected today across the southern Plains including DFW to OKC to Tulsa to Springfield! This could be one of the more significant #tornado events for the southern Plains in a decade. Stay tuned to severe weather watches and warnings in the moderate risk area.
Live emergency update on tornado outbreak expected today across the southern Plains including DFW to OKC to Tulsa to Springfield! This could be one of the more significant #tornado events for the southern Plains in a decade. Stay tuned to severe weather watches and warnings in the moderate risk area.
It's also a "possible" watch at 60% assurance. Possible that the watch might not be posted
Kds86z
Member
Oh it’s happening..
WhirlingWx
Member
I took these screenshots when it was north of Preston, KS
Attachments
Kds86z
Member
Gordon TX. Hasn’t been mentioned much.
Kds86z
Member
jiharris0220
Member
Yesterday verified as a moderate risk, as expected, the cloud/fog cover did nothing to deter the development of dryline convection.
The storm in Oklahoma after if produced a couple of short lived tornadoes struggled from mid level dry air as the only support it had was nebulous forcing. Which left it with no supporting convection to reinforce it which made it susceptible to dry air entrainment enhanced by the LLJ.
The dryline cells in Kansas and Nebraska were closer to the trough and therefore had a stronger forcing mechanism, and therefore more mini supercells to merge with and keep them going. Inversion layer was weaker in these locations as well looking at the Skew Ts.
I would say the hrrr verified, but every cam model pretty much had the same solution, although they underestimated the strength of the inversion layer in Oklahoma.
Remember, while cloud decks can prevent destabilization, in the face of a strong LLJ, a lot of the stability can be mixed out, which is what happened when night fell. (Important footnote: even where the cloud deck was present, the atmosphere was still plenty unstable, laspe rates were in between 5.5 to 6.5 c/km, which isn’t great, but still sufficient for tornado production).
It also helps that this was dry line convection, not OWS convection, as OWS convection is completely at the mercy of how much destabilization occurs to allow confluence bands to initiate in the first place, and then having to break through the inversion layer.
While dry line convection also needs sufficient destabilization, the forcing from the trough and or convergence along the front negates the total reliance on sufficient destabilization.
Which is why the cells in Kansas were able to put down wedges despite the cloud cover throughout the day, while western Oklahoma completed cleared out and the convection still died.
The storm in Oklahoma after if produced a couple of short lived tornadoes struggled from mid level dry air as the only support it had was nebulous forcing. Which left it with no supporting convection to reinforce it which made it susceptible to dry air entrainment enhanced by the LLJ.
The dryline cells in Kansas and Nebraska were closer to the trough and therefore had a stronger forcing mechanism, and therefore more mini supercells to merge with and keep them going. Inversion layer was weaker in these locations as well looking at the Skew Ts.
I would say the hrrr verified, but every cam model pretty much had the same solution, although they underestimated the strength of the inversion layer in Oklahoma.
Remember, while cloud decks can prevent destabilization, in the face of a strong LLJ, a lot of the stability can be mixed out, which is what happened when night fell. (Important footnote: even where the cloud deck was present, the atmosphere was still plenty unstable, laspe rates were in between 5.5 to 6.5 c/km, which isn’t great, but still sufficient for tornado production).
It also helps that this was dry line convection, not OWS convection, as OWS convection is completely at the mercy of how much destabilization occurs to allow confluence bands to initiate in the first place, and then having to break through the inversion layer.
While dry line convection also needs sufficient destabilization, the forcing from the trough and or convergence along the front negates the total reliance on sufficient destabilization.
Which is why the cells in Kansas were able to put down wedges despite the cloud cover throughout the day, while western Oklahoma completed cleared out and the convection still died.
Last edited:
UpperLevelLOL
Member
Ozonelayer
Member
I will say, confidence in the main storm mode being semi discrete/discrete is increasing quite a bit. Ever since the 10z, semi discrete supercells were being shown and ever since the 12z, discrete supercells are being shown. The 14z and 15z specifically look quite unfun.
15z HRRR
14z HRRR
15z HRRR
14z HRRR
Attachments
Kds86z
Member
Getting less messy?
Ozonelayer
Member
Precisely.
Kds86z
Member
UpperLevelLOL
Member
Pretty crappy to put a pink color in the thumbnail when this isn't high risk
